Reciprocating pump



y 2 R. s. c. SMITH RECIPROCATING PUMP Filed Sept. 18, 1959 hmmmamm V IINVENT R m; S. c.

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ATTORNE Y United States Patent 3,943,235 REQEPROCA'HNG PUD/l1 RobertSidney Claridge Eirnith, Chislehurst, Kent, England, assignor to JohnSelby Hillyer, Kent, England Filed Sept. 18, 1959, Ser. No. 848,867 8Claims. (til. 103-492) The present invention relates to reciprocatingpumps of the kind adapted to deliver fluid in both directions ofrelative axial movement of the inner and outer members with respect toone another.

It is an object of the present invention to provide practical means ofconstructing a pumping element so as to enable an appreciably smalleffective annular area to be presented against the fluid under deliveryin each direction of axial movement of the inner and outer matingmembers with respect to each other.

It is also an object of the invention to provide a pump which willdeliver fluid under substantially high Working pressures in eachdirection of relative axial movement of the inner and outer members withrespect to each other without requiring more than small operatingforces.

It is a further object of the invention to provide a pumping element inwhich substantially the whole of the internal delivery space can beswept clear of fluid in each direction at the termination of each fullaxial movement between the inner and outer members.

It is yet a further object of the invention to provide improved means ofsupporting the internal members of such pumps against excessive side orradially applied loads reacting at right angles to the pumping element.

A preferred constructional embodiment of this invention, as applied to asmall hand pump, will now be described by way of example with referenceto the accompanying drawing wln'ch is a view partly in longitudinalcross-section and partly in side elevation of such a hand pump.

The pump illustrated in the drawing has an inner assembly comprising twolengths of brass tube 11, 12 of slightly different external diameterswhich are coaxially interconnected by a junction piece 13, 14. The part13 of the junction piece, which has a plain cylindrical outer surface ofslightly smaller external diameter than the brass tube 12, is inserted ashort distance into the bore of the tube 11 and is secured therein bysoldering. The other part 14 of the junction piece is externallyscrew-threaded, screwed into the tube 12 and secured by a lock nut 15.The part 13 of the junction piece provides an annular gap between thecylindrical surfaces of the tube portions 11 and '12. A central axialbore 16 extends through the part14 of the junction piece and through thepart 13 thereof as far as the position where the part 13 enters the tube11. At this position, it has a closed end 17. Immediately adjacent theend of the tube 11 in which the part 13 is soldered, radial bores 18 aredrilled in the part 13 so as to interconnect the closed end of the bore16 with the outside of the part 13.

At the end remote fro-m the tube 12, the tube 111 is provided with ashort extension piece 19 carrying a handle (not shown) at its outer endand formed with a flange 21 on the end thereof adjoining the tube 11.

The end of the tube 12 remote from the tube 11 is externallyscrew-threaded at 22 to receive a stop nut 23 and an associated lock nut24. The screw-threaded part 22 may also serve for the attachment of aspraying nozzl (not shown).

The inner assembly comprising the tubes 11, 12 .is housed within anouter assembly comprising a brass tube 25 which is slightly shorter thaneither the tube 11 or the tube 12 and has an internal diameter slightlygreater than the external diameter of either of these last-mentioned3,43,235 Patented Jul in, race ice washers 37, 38, a neck ring 39 and agland ring 41 is accommodated within the housing 27. The O-rings 3-1 and36 co-operate respectively 'with the outer surfaces of the brass tubes11 and 12.

A radial inlet port 42 is drilled in the housing 27 immediately adjacentthe corresponding end of the tube 25. Brazed to the housing 27 so thatit'coaxially surrounds the outer end of the port 42 is an internallyscrew-threaded socket 43, into which is screwed a valve housing 44having an extension 45 for'connection to a flexible hose (not shown).Within the valve housing 44 is arranged a nonreturn valve consisting ofa ball 45 which is urged towards a seating 47 by a spring 48. An axialbore 49 drilled through the extension 45 opens through the middle of theseating 47.

A baffle, in the form of a tubular member 51 of nylon formed with acircumferential groove to accommodate a sealing ring 52 cooperating withthe bore ofthe brass tube 25, surrounds the part 13 of the junctionpiece 13, 14 and is capable of limited axial movement within the gapbetween end surfaces of the tube 11 and the lock 'nut 15. An appreciableannular clearance is provided between the external cylindrical surfaceof the part 13 and the internal surface of the member 51. At the endnearer the tube 11 the member 51 has its inner edge charnfered as at 53.Radial grooves 54 are also form edin the member 51 at this end toprevent it from seating against .the

end of the tube 11. The other end 55 of the member 51 is adapted toco-operate with the end 56 of the lock nut 15, so that, when the member51 is pressed against the lock back, i.e. to the left as seen in FIG. 1,the baffle member 51 is displaced so that its surface 55 seals againstthe surface 5 6 on the lock nut 15 with the result that fluid is drawnin through the bore 4? and past the valve 46 into the chamber 57. Then,on reversal of the direction of movement of the inner assembly, thevalve 46 closes and the battle member 51 is displaced to disengage thesurfaces 55, 56

so that fluid is transferred from the chamber 57 to the chamber 58between the surfaces 55, 56, through the annular clearance between thebafile member 51 and the part 13 and through the radial grooves 54.Since the volume of the chamber 57 is reduced more rapidly than that ofthe chamber 58 is increased, fluid will also be discharged through thebores 18 into the bore 16. On further reversal, the surfaces 55, 56 areonce again sealed together and, while fluid is drawn into the chamber 57past the valve 46, fluid is also transferred from the chamber 58 intothe bore 16 via the radial grooves 54 and the radial bores 18. It willbe observed that while suction occurs in only one direction of movement,i.e. when the inner assembly is moved to the left in the drawing,delivery through the bore 16 occurs during both directions of movement.

The length of stroke of the pump is limited at one end by the nut 23abutting against the gland nut 29 and at the other end by the flange 21abutting against the gland nut 28. The positions of the nut 23 and theflange 21 relative to the baffle member 51 are such that the chambers 57and 58 are almost completely emptied during alternate strokes of thepump.

The sizes of the respective working surfaces may be so arranged that,while the quantity delivered may be substana the two members.

aocaass tially equal in both directions of motion of the inner assemblywith respect to the oute r assembly, it may, also be kept suificientlylow to enable very high pressures to be developed at the deliveryconnection, i.e. in the part 22, Without itbeing necessary to exert morethan relatively small forces to operate the pump. Thus, for example, the

internal diameter offthe tube 25 may be 1.001 inch, the externaldiameter of the tube 11 1.080 inch and that of the tube .999 inch. a T

Van'ousmodifications may be made in the pump described above withoutexceeding the scope of the present inventionas defined in the appendedclaims. Thus, for

example, two Working surfaces of diiferent diameter may be provided onthe outer member and a working surface of uniform diameter on the innermember. In this case the bafiie may -be located in an interruptionbetween the working surfaces of the outer member and arranged to sealagainst the working surface of the inner memberyand the sealing meansmay be carried by the inner member and arranged to seal against theworking surfaces-of the outer member. Furthermore, the non-return valvefor the transfer of fluid from the annular space of larger radialthickness to that'of smaller radial thickness, instead of beingconstituted by an end surface of the baflie whichis engaged with anddisengaged from a seatingaccordingto the axial position of the baflie,may be constituted by a separate non-return valve incorporatedin thebaflie. Yet;

further alternatively the baflie maybe constructed so as to j preventthe flow of fluid pastthe baffle in either direction in which case anon-return valve is provided to act in vconjunction with the baflie butmay be located eitherof The 'fluidinlet and outlet connections may belocated according to convenience either both' in the first member orboth in the second member or alternativelywith the tively with the inletin the second member and theoutlet connection in the first memberirrespective in each case I of the relative disposition of the twomembers as to whetherthe first be within the second or the second be thefirst, provided always that the inlet connect 4 a p connectionconnectedfor the discharge of fluid from the annular space of smallerradial thickness; a

2. .A reciprocating pump asjclaimed in claim 1, wherein the baffle isretained in a position between the working surfaces of said othermember.

3. A reciprocating pump as claimed in claim l, wherein the workingsurface'of said one member is of shorter length than the workingsurfaces of said other member.

4. A reciprocating pump as claimed in claim 1, and further comprisingbearings for slidably supporting said other member, said bearings beingcombined with the sealing means carried by said one member. I

5. A reciprocating pump comprising two elongated members arranged forrelative sliding movement one within the other, one of said membershaving a cylindrical working surface of uniform diameter and the otherof said members having two coaxial Working surfaces of differentdiameters. to one another and to the working surface of baflie locatedbetween the two Working surfaces of said other member and forming a sealagainst the working surface of said one member, said baflie being freeto move axiallyv through a limited distance, a non-return inlet valveconnected for the supply of fluid to the annular space of larger radialthickness, a non-return delivery valve arranged to permit transfer offluid past said baffle in the direction from the annular" space oflarger radial thickness to that of smaller radial thickness, saidnon-return delivery valve comprising an end surface of said bafflefacing the annular. space of larger radial thickness and a seatingsurface carried "by said other member and arranged, when the baflle isin its end position near the annular space of larger radial thickness,to be engaged by the said end surface of the battle and thereby'to sealthis last i mentioned space from the space of smaller radial thickwiththe annular chamber bounded by thesurfaces'having the greater diametraldimensional difference and the outlet connect with the annular chamberbounded by the surfaces having the smaller diametral dimensionaldifference.

According to the invention the pump may beprovided ,4 with a non-returnvalve at the fluid inlet, This valve may be located either in the firstorsecond member irrespective of their relative dispositions.

- In the caseof power operated pumps a plurality of elearrangements.

I claim:

1. A reciprocating pump comprising two elongated members arranged forrelative sliding movement one within the. other, one of said membershaving a cylindrical 'working surface of uniform diameter and the otherof said ments may be employed to provide either radial or axial vsmaller radial thickness respectively are formed between 7 the workingsurfaces of said one member and said other member, sealing means securedto said one member at opposite ends of its working surface andco-operating respectively with, the two working surfaces of said othermember to sealthe outer ends of said annular spaces, a baflie locatedbetween the two working surfaces of said other member and forming a sealagainst the working surface of said one member, a non-return inlet valveconnected for the supply of fluid to the annular space of larger radialthickness, valve means form-ing a non-return delivery valve arranged topermit transfer of fluid past said baffle in the direction from the'annular space of largerradial thickness to that of smaller radialthickness, and an outlet ness, and an outlet connection connected forthe discharge 7 of fluid from the annular space of smaller radialthickness.

6. A reciprocating pump comprising an outer clongated tubular memberhaving an internal cylindrical working surface of uniform diameter, aninner elongated member having'twoexternal cylindrical working surfacesarranged coaxially on dilferentlinear portions thereof, the diameters ofsaid two external Working surfaces being fractionally different from oneanother and the larger of them being fractionally smaller than thediameter of .the working surface of the outer tubular member so' thatannular spaces of larger and smaller radial thickness respectively areformed between the working surfaces of said inner and outer members,sealing .means secured to said outer tubular'member at opposite ends ofits working surface and co-operating fer of fluid past said *baflle fromthe annular space of the outlet connection emerges from the pump at theend of the inner member remote from the working surface of largerdiameter and includes a passage for-med axially through the inner memberto a point. beyond said baffle 5 and is connected to the annular spaceof smaller radial thickness.

8. A reciprocating pump as claimed in claim 6, Wherein the inner membercomprises two tubes on which its two working surfaces are provided, ajunction piece interconnecting said two tubes in end-to-end relationshipand providing an annular 'gap between them, the baflie being arranged sothat it loosely surrounds the junction piece within said gap and iscapable of limited axial movement, so that, in its end position nearerthe smaller of the two tubes, its end face engages a valve seating sur-6 face on the smaller tube to seal the space of larger radial thicknessfrom the space of smaller radial thickness and so that in its other endposition fluid can pass from the space of larger radial thickness andthrough the clearance between the baffle and the junction piece to thespace of smaller radial thickness.

References Cited in the file of this patent UNITED STATES PATENTS Wise sJuly 6, 1954

